Seal for a high pressure, short arc gas lamp

ABSTRACT

The invention concerns a reliable quartz-to-metal seal for use in a high pressure, short arc gas lamp, suh as for example, that disclosed in Keller et al. U.S. Pat. No. 3,256,459. The seal involves a nickel ferrule to provide a long path nickel-to-quartz and nickel-to-tungsten seal.

United States Patent 1191 Rich [4 Aug. 7, 1973 SEAL FOR A HIGH PRESSURE, SHORT ARC GAS LAMP [5 6] References Cited [75] Inventor: Charles E. Rich, Gainesville, Fla. UN ED ST S P T S ig e h U i e Sa es f Am ica as 'Nolte ted b th S ta fth 3,198,875 8/l965 Keller 174/5063 X ,3 e o e 3,555,340 1/1971 Peacher et al. 313/220 x Army, Washmgton, D.C. [22] Filed: June 12 1972 Primary Examiner-Laramie E.Askin ll [21,] App. No: 261,858-- gttgirney Harry M. Saragovitz, Edward J Ke y a 1571"" issTRAci [52] 174/5058 53? The invention concerns a reliable quartz-to-metal seal [51] Int Cl n 5/32, j for use in a high pressure, short are gas lamp, suh as for t. N I 58 Field ofSearch.., 174/1705, l7.08, example that dscmsed Keller et 31 U S Pd 0 SILVER AND NICKEL NICKEL METALIZED 2O LAYERS 14 3,256,459. The seal involves a nickel ferrule to provide a long path nickel-to-quartz and nickel-to-tungsten seal.

1 Claim, 1 Drawing Figure IOQUARTZ Bio/f TUNGSTEN PATENTED H973 VER A NICKEL NICKEL METawgggm KIOQUARTZ KY5 %\N\\\N\\\N\\ TUNGSTEN NICKEL SEAL Fort An on PRESSURE, SHORTARC GAS LAMP BACKGROUND OF INVENTION vention to provide a lamp having a nickel ferrule interfaced betweenthe tungsten electrode and the quartz envelope.

Another object of the invention is to provide a substantially rigid support for the tungsten electrodes.

A further object of the invention is to prevent phase changes in the tungsten electrodes by providing; a seal structure which requires less heat for assembly.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing is a section illustrating the seal of the invention as applied to one end of a lamp of the type described.

DETAILED DESCRIPTION OF THE INVENTION LII Referring now to the drawing, 10 indicates a quartz tube which constitutes the outer envelope of the lamp in question. The outer half of the end surface 12 and the outer-surface 14 of the tube I0 are metalized by successive thin layers of nickel and silver in a manner well known in the art for a distance of approximately 0.025 inch.

The tube 10 is provided with a groove 16 adjacent its end. A pure nickel ferrule 18 is positioned on the end of the tube 10 for proper overall length and concentricity and deformed into the groove 16 as indicated at 20. Before positioning, the inner surface of the ferrule 18 is plated with silver and subsequent to. the positioning 7 of the ferrule, the ferrule 18 is joined to the tube.l0 by soldering with pure tin-or five percent indium lead solder. This process produces a seal which will withstand pressures of better than 400 psi and is vacuum tight.

A tungsten lead 30 is bonded into the opening of a central boss of a nickel insert generally indicated 34. The insert comprises the boss 32, a conical portion 36 and a cylindrical skirt 38. The outer diameter of the skirt 38 is such that the insert will slide into the tube 10. The insert 34 is positioned within the end of the tube 10 so that the tungsten lead-is properly located and the skirt 38 is then welded to the ferrule 18 in the area indicated generally 40 by a shielded arc process (Heliarc).

The end of the quartz tube is thus completely sealed through a combination of a nickel-to-quartz seal and a nickel-, to-tungsten seal. Neither of these seals requires a particularly high heat process so that any phase changes of the tungsten due to excessive heat is eliminated. Further, the conical nickel insert provides a rigid strong support of the tungsten lead 30.

I claim:

1. seal for a short are high pressure lamp structure comprising a quartz tube,

the outer surface of the end portions of said tubebeing metalized by successive layers of nickel and silver,

an annular groove formed in the outer surface of said tube adjacent the metalized portion,

a nickel ferrule positioned surrounding oneend of said tube,.

said ferrule being deformed into said groove and soldered to said metalized area,

a frusto conical nickel insert positioned within said one end of said tube with the wide end thereof welded to said ferrule, and

a tungsten electrode protruding through the narrow end of said insert and sealed thereto. 

